#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  string A, B;
  cin >> A >> B;
  function check = [](string s) {
    for (int i = 0; i < (int)s.size(); i++) {
      if (!('0' <= s[i] && s[i] <= '9')) return false;
    }
    int x = stoi(s);
    return x <= 12345 && !((int)s.size() > 1 && s[0] == '0');
  };
  if (check(A) && check(B)) {
    cout << "OK" << '\n';
  } else {
    cout << "NG" << '\n';
  }
  return 0;
}